1. Field of The Invention
The invention relates to a medical device of the type for generating a therapeutic value for a patient as a function of at least one variable parameter picked up within the body and constituting a first input value, with a change in the first parameter being a function of a second parameter which also constitutes an input value.
2. Background Information
In such devices which generate a therapeutic value for a patient from a value (parameter) picked up within the patient's body, there often exists the problem that this parameter, with the aid of which the patient is treated, is a function of another parameter about which no reliable knowledge is available in connection with the intended treatment to enable it to be used as a further variable in the course of the treatment or which cannot be considered for other reasons. Since the further parameter thus takes on a relatively random value in each case, success of the treatment cannot be ensured with the necessary reliability.
Thus, it has not yet been possible in connection with cardiac pacemakers to provide a reliable rule for influencing the stimulation rate with maximum efficiency as a function of conductivity values that were picked up in the heart within the cardiac cycle at certain points in time during the pre-ejection period.
The obtained values differed greatly from patient to patient so that the transfer of settings found for one patient to another patient was increasingly connected with difficulties.
Usually it was the increase in conductivity that was evaluated, determined by electrodes installed in the right ventricle which preferably may simultaneously constitute electrodes of the stimulation system.